1967 Plymouth Belvedere GTX - Two Jacks Beat A King

By the time automotive designer Jack Irons Jr. was in seventh grade, he knew what car he wanted. His father, Jack Irons Sr., had amassed a collection of old Mopars and wanted to save one for his son as a project.

Jack Sr. purchased the B-Body in Troy, Michigan, from friend and original owner, Ron Rizzo, in 1987. The car had been hit in the rear quarter-panel in 1973, and sat unrepaired until it was purchased by the elder Irons. This "time in waiting" took its toll on the car and rusted out the bottom half of the quarters. The doors had rust, and the front framerail had become weak. It was a good car to start with, but the younger Irons would have his work cut out for him when he eventually found time to dedicate to the project.

It wasn't until the winter of 2000 that the younger Irons was able to tear into the car and completely strip it for the restoration. But then school and other projects began to take up his time, so the car had to sit yet again. The revitalization of the project didn't come until December 2005, when father and son inspected every inch of the car and concluded the car's front framerails were too rusty and not capable of handling the power that would be thrown at it. So the younger Irons fabricated new framerails as well as chromemoly subframe connectors to tie the front and rear framerails together. His schooling paid off when he was able to design a 12-point rollcage using 3D CAD software. The NHRA-certified rollcage was designed to be welded to the frame structure rather than the sheetmetal floor.

With the lion's share of the chassis work taken care of, the elder Irons took over with the bodywork, paint, and body panel installation. New quarter-panels were welded on, and the car was bolted to a homemade rotisserie. Then the entire car was media-blasted to strip all the original paint and prepare it for the bodywork. The elder Irons provided "laser-straight" results to the entire car before he covered it in a color that can only be called Sinister Black. The car was removed from the rotisserie, and the new front suspension was attached. During this assembly process, the old, factory rear suspension was used temporarily just to get the car rolling.

Jack Irons Jr.'s then-girlfriend, Allison, focused on the interior. She reupholstered the seats with Legendary Auto Interiors covers, replaced the carpet, and prepped the rest of the original interior items for installation. In an effort to make the driver and the lucky passenger feel a bit safer in the car, the factory seats are equipped with racing harnesses-a must for the quarter-mile speeds this GTX is capable of. The factory steering wheel and even the back seat were left in place. Jack Irons Sr. says, "We wanted to retain as much of the original appearance as possible." The audio system was also upgraded with a hidden iPod connection and Polk 6x9 speakers wired to the factory radio controls.

The GTX receives its temporary motivation from a 500ci Chrysler RB big-block. The younger Irons tossed the factory internals for quality performance parts. The cast-iron block was punched out to a 4.370-inch bore, and the main journals received billet caps. A forged-steel, 4.150-inch, Callies crankshaft spins inside the mains. Finally, 11.0:1 compression CP pistons and factory length GRP aluminum connecting rods were used to round out the bottom end.

The factory iron heads were replaced in favor of aluminum Indy cylinder heads. These were treated to a Max Wedge port and feature Manly 2.19-inch intake and 1.81-inch exhaust valves with LSM valvesprings. Controlling the valve events is a secret spec LSM mechanical roller camshaft and 1.6-ratio Indy aluminum roller rocker arms. This was all topped off with an Indy 440-2 intake manifold and Holley 850 carburetor.

The car was wired with two separate ignition systems, including two coils. One was specifically for street use, and the other was tailored for racing. While on the street, an MSD Blaster HVC Coil and MSD 6AL control the spark and provide more than adequate power supply. In anticipation of the next engine, an additional, more hardcore ignition system was installed, which consists of an MSD Blaster Coil HVC II Coil accompanied by an MSD Digital-7 programmable ignition control unit. With two ignition setups, it's easy for the younger Irons to get the car ready for the strip and not have to make a sacrifice on the street. Hooker 2-inch exhaust headers provide the 500 ci with a means of exhaling. These ceramic-coated headers feature 3 1/2-inch collectors and spit out into 45-degree dumps. The younger Irons also rebuilt the factory Hemi four-speed transmission to support the new, healthy dose of power.

After the car was running, the younger Irons opted to enhance the appearance of the Belvedere with a custom hood. He designed and built a 4 1/2-inch RO Super Stock fiberglass hoodscoop. He mounted this to a bolt-on fiberglass AAR hood, which was sprayed the body color to complete the bodywork and paint. The overall appearance of the car is menacing when combined with the rake in the car's stance.

All of this power needed to find its way to the ground somehow, so the younger Irons built a custom triangulated four-link suspension to control the rear, while the front suspension was enough to support his needs. The two Jacks installed QA1 12-way adjustable shocks in both the front and rear of the car. A Dana 60 sits out back with factory axles, 4.30 gears, and a Sure Grip unit. To complete this package, a set of American Racing Pro-Series wheels was installed. The 15x4 fronts were wrapped in Mickey Thompson Front Runners and the 15x8-inch rears saw a set of 29x11.5 Hoosier Quick Time Pros. Wilwood Drag Race four-piston calipers and brakes are used to bring the 3,450 pounds to a halt.

All the work from start to finish was perfomed by father and son in the Irons' family shop. Jack Sr. says, "The only thing we didn't do is the front wheel alignment." It was a pure collaborative family effort to complete the car, and the younger Irons hits the streets of Michigan whenever he has the chance; he even drove it on his wedding day.

The elder Irons stressed to his son that he should build a car that could be enjoyed on the street just as much as on the track. Lucky for us, he listened to his father and built this GTX as a multi-role fighter. It's tame enough to be driven on the streets, and monstrous enough to cause some serious trouble at the dragstrip.

Since our photo shoot, Jack Jr. has gained a thirst for more power. He plans to build a single-turbo RB-block with Indy heads in the near future and is hoping for 1,000 horsepower. Good luck, Jack.

Fast Facts'67 Plymouth Belvedere GTXJack Irons Jr.Ortonville, MI

Mopar Power

Engine: The engine was built by Jack Irons Jr. This RB-block has a 4.370 bore and 4.150 stroke, good for 500 ci. Billet main caps, GRP aluminum connecting rods, CP 11.0:1 pistons, and a forged-steel Callies crankshaft make up the bottom end. The cylinder heads are Indy aluminum heads with a full race max wedge port. These heads feature Manley 2.19-inch intake/1.81-inch exhaust valves. The camshaft is an LSM mechanical roller with a top secret grind. Indy also supplied the 1.6-ratio aluminum roller rockers, while LSM was used for the valvesprings. The air gets sucked in through an Indy 440-2 intake manifold and Holley 850 carburetor. It then exhales through a set of ceramic-coated Hooker headers with 2-inch primaries and 3 1/2 -inch collectors. Street ignition is handled by an MSD Blaster HVC coil and MSD 6AL. A separate ignition system is used for racing, which is comprised of a MSD Blaster Coil HVC II Coil and a MSD Digital-7 programmable ignition control unit.Transmission: Jack Irons Jr. rebuilt the factory Hemi four-speed to handle all the power.Rearend: A Dana 60 sits out back with stock axles, 4.30 gears, and a Sure Grip.

Sure Grip

Chassis: The front framerails were entirely replaced and designed by Jack Irons Jr. He also used 3D CAD software to design an NHRA-certified, 12-point rollcage that incorporates the custom subframe connectors, also his design.
Suspension: Factory front suspension with 12-way adjustable QA1 shocks and a triangulated four-link rear suspension with 12-way adjustable QA1 shocks.Brakes: Wilwood Drag Brakes with four-piston calipers all around.Wheels: American Racing Pro Series wheels: 15x4 front wheels with 27.5x4.5 Mickey Thompson front runners and 15x8 rear wheels with 29x11.5 Hoosier Quick Time Pros.

High Impact

Body: 1967 Plymouth GTX. Jack Irons Sr. completed the bodywork and paint. Jack Irons Jr. designed a one-off, 4 1/2-inch, RO-style, Super Stock hoodscoop attached to an AAR bolt-on hood.Interior: The original interior has been completely restored by Jack Irons Jr. and his wife, Allison. The black vinyl and black carpet are from Legendary Auto Interiors.Sound system: The factory radio has a hidden iPod adaptor, and the speakers have been upgraded to Polk 6x9s.